package com.simple.nio.selector;

import org.junit.Test;

import java.io.IOException;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.SelectionKey;
import java.nio.channels.Selector;
import java.nio.channels.ServerSocketChannel;
import java.nio.channels.SocketChannel;
import java.util.Date;
import java.util.Iterator;
import java.util.Scanner;

/**
 * 功能描述:
 *
 * @author: WuChengXing
 * @create: 2021-12-13 15:58
 **/
public class SelectorSendMsgTest {

    public static void main(String[] args) throws IOException {
        //1. 获取通道
        SocketChannel sChannel = SocketChannel.open(new InetSocketAddress("127.0.0.1", 9898));
        //2. 切换非阻塞模式
        sChannel.configureBlocking(false);
        //3. 分配指定大小的缓冲区
        ByteBuffer buf = ByteBuffer.allocate(1024);
        ByteBuffer readBuf = ByteBuffer.allocate(1024);
        //4. 发送数据给服务端
        Scanner scan = new Scanner(System.in);
        while (scan.hasNext()) {
            // 先读取数据
            int len = 0;
            while ((len = sChannel.read(readBuf)) > 0) {
                buf.flip();
                System.out.println(new String(readBuf.array(), 0, len));
                buf.clear();
            }
            String str = scan.next();
            buf.put((new Date() + "\n" + str).getBytes());
            buf.flip();
            sChannel.write(buf);
            buf.clear();
        }
        //5. 关闭通道
        sChannel.close();
    }


    @Test
    public void server() throws IOException {
        //1. 获取通道
        ServerSocketChannel ssChannel = ServerSocketChannel.open();
        //2. 切换非阻塞模式
        ssChannel.configureBlocking(false);
        //3. 绑定连接
        ssChannel.bind(new InetSocketAddress(9898));
        //4. 获取选择器
        Selector selector = Selector.open();
        //5. 将通道注册到选择器上, 并且指定“监听接收事件”
        ssChannel.register(selector, SelectionKey.OP_ACCEPT);
        //6. 轮询式的获取选择器上已经“准备就绪”的事件
        while (selector.select() > 0) {
            //7. 获取当前选择器中所有注册的“选择键(已就绪的监听事件)”
            Iterator<SelectionKey> it = selector.selectedKeys().iterator();
            while (it.hasNext()) {
                //8. 获取准备“就绪”的是事件
                SelectionKey sk = it.next();
                //9. 判断具体是什么事件准备就绪
                if (sk.isAcceptable()) {
                    //10. 若“接收就绪”，获取客户端连接
                    SocketChannel sChannel = ssChannel.accept();
                    //11. 切换非阻塞模式
                    sChannel.configureBlocking(false);
                    //12. 将该通道注册到选择器上（上一步算是已经创建了一个长连接）
                    sChannel.register(selector, SelectionKey.OP_READ);
                } else if (sk.isReadable()) {
                    //13. 获取当前选择器上“读就绪”状态的通道
                    SocketChannel sChannel = (SocketChannel) sk.channel();
                    System.out.println("是读取类型，这里就是来出来上次连接来的数据：" + sChannel.getRemoteAddress());
                    //14. 读取数据
                    ByteBuffer buf = ByteBuffer.allocate(1024);
                    int len = 0;
                    while ((len = sChannel.read(buf)) > 0) {
                        buf.flip();
                        System.out.println(new String(buf.array(), 0, len));
                        buf.clear();
                    }
                    System.out.println("我读完了，现在写点数据回去");
                    sk.interestOps(SelectionKey.OP_WRITE);
                } else if (sk.isWritable()) {
                    ByteBuffer buf = ByteBuffer.allocate(1024);
                    buf.put("received".getBytes());
                    buf.flip();
                    SocketChannel socketChannel = (SocketChannel) sk.channel();
                    socketChannel.write(buf);
                    // 这里写完之后需要切回读操作，让客户端能够继续写数据
                    sk.interestOps(SelectionKey.OP_READ);
                    System.out.println("写操作，只对读感兴趣");
                }
                //15. 取消选择键 SelectionKey
                it.remove();
            }
        }
    }
}
